Kala Azar

What is Kala azar?

Kala azar is a slow advancing and naturally occurring disease that is caused by a protozoan parasite of Leishmania genus. In India, the only parasite that causes this disease is Leishmania donovani. The parasite mainly infects the reticuloendothelial system and can also be found in abundance in bone marrow, liver and spleen.

The condition when Leishmania donovani invades skin cells, stays and develops and shows dermal leisions is known as Post Kala-azar Dermal Leishmaniasis (PKDL). Certain kala-azar cases show PKDL after a few years of treatment. According to recent studies, PKDL may appear without passing through visceral stage. However, satisfying data is yet to be produced in the course of PKDL.

Kala-Azar Symptoms

  • Loss of interest and desire of everything, pale appearance, loss of weight with weakness.
  • Abnormal enlargement of the spleen, usually nontender and soft.
  • Dry, skin and scaly skin of hands, abdomen, feet and face that gives the Indian name Kala-azar which means ‘Black Fever’.
  • Anaemia(a condition of deficiency of haemoglobin or red cells in the blood) progresses rapidly.
  • Anaemia along with emaciation(weakness) creates a typical appearance of the affected person.

How Kala-azar is Diagnosed?


A condition of fever lasting for more than two weeks and not responding to antibiotics and antimalarials. Clinical laboratory searches may include spreading leucopenia thrombocytopenia and anaemia.


Serology tests: Different tests are available for diagnosis of Kala-azar. The mostly used tests are based on relative sensitivity, while operational feasibility involves Direct Agglutination Test (DAT), ELISA and rk39 dipstick. Aldehyde Test is usually applied but it is a nonspecific test. IgM (immunoglobulins M)tests are under development and not available for use.

Confirmatory diagnosis is  Parasite demonstration in spleen/bone marrow or culture medium. However, sensitivity varies with the organ chosen for aspiration. Though spleen has the most sensitivity and specificity, a skilled professional with appropriate precautions can perform well only at a well-equipped hospital.

To know more about Kala-azar disease and any other concepts related to Biology, visit BYJU’S.

Quiz On Kala Azar

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